TasasK - I strongly agree with Imafan about having a soil test done.
Penn State is your Land Grant University. On the left side there is a link for submitting samples.
Once the test is completed either contact the University (contact link on the site) or your county agent to have the report translated into plain English and for recommendation on correcting any problems.
For example - Elemental Sulfur is frequently used to reduce sol pH. Bluberries require a very low/acidic pH. The problem is knowing exactly how much to apply. That is why that follow up call is important.
For a Master Gardener project I did comparisons of results from both home test kits and lab test. A pH meter (not the strips or tablets) gave very accurate readings when used according to the directions. The home test kits for nutrients were way off when compared to a lab test.
This link has very basic information on fertilizer.
https://www.ehow.com/facts_5798477_basic ... zers_.html
What you are growing and the growing conditions will determine what and how much you need. I have a large, old live oak in the back yard that sucks nitrogen out of the soil . I apply Ammonium Nitrate 3 times each year. I purchase it in 50 lb. sacks from a feed and seed store and store it in sealed, 5 gallon buckets.
G insist on using a weed and feed on the front lawn. I have convinced him not to use it in the back because of the oak tree, young Satsuma and the herb and vegetable garden.
I use the Ammonium Nitrate under the oak tree and on the back lawn. I fertilize the Satsuma with 8-8-8 mid February and again early May. In the vegetable and herb garden I usually just add compost. Because of health issues I neglected my compost bins and do not have any cooked compost so I will use a water soluble fertilizer with very low N. P is the highest number.
G uses a walk-behind broadcast spreader in the front. In the back I use a hand held spreader for under the oak tree and the lawn. I fertilize the Satsuma using a 2 lb. peanut butter jar with holes drilled in the lid. For the vegetable and herb garden I use a hose end jar to apply the water soluble fertilizer.
Container plants are another issue. I have lots of container plants on the patio and hanging baskets in the tree. Again what I use depends on the plant. Green plants get a water soluble fertilizer with a high N. We have a very long growing season so they get fed 2 or 3 times a year. Flowering plants get a water soluble fertilizer with a high P - often labeled "Bloom Booster" or "Super Bloom". On flowering plants I use the bloom buster once - early spring - then use Epsom salt - 1 tbsp. per gallon of water once per month.
Some plants - like Bougainville - thrive on neglect. They do best when allowed to dry out completely between watering and will stop blooming if any nitrogen is added. I use only Epsom salt on those babies.
In addition to the information on soil testing the Penn State site has many links on home gardening, lawn care and landscaping. Put their page on your favorites bar. A wonderful resource. IDK about PA but in Lafayette, Louisiana we have a very responsive Extension Office System. Our County Agents are Amazing
! They actually answer their phone and respond to e-mails ASAP. They even make home visits at no cost. In addition there is a large, active Master Gardener Association with members on hand to answer questions. Unfortunately that is not always the case.
Sorry for the ramble.
Hope some of this is helpful.
BTW - you did mention that organic is not a requirement. If you want to use organic products there are many available. Penn State or your CA can give you recommendation for your region.